Some of this natural plutonium is related to uranium. Some has been found in meteorite dust deposited in the seabed. So, plutonium-244 is the heaviest naturally occurring element that we know of.

Given plutonium’s long half-life, we humans have permanently altered what once was our natural environment. We no longer live in an environment of purely natural background radiation.

Instead, the tremendous heat generated by the natural decay of plutonium-238—up to 475º F in the New Horizons probe—is converted to electricity in a radioisotopic thermal generator (RTG).

This plutonium scientist is trying to stop that ... Natural uranium is 99.3% Uranium 238 -- a particular variety of the element with 238 protons and neutrons.

Plutonium-238 is 280 times more radioactive than Plutonium-239, the plutonium isotope used in atomic bombs and as a “trigger” in hydrogen bombs. There are 10.6 pounds of Plutonium-238 on ...

Furthermore, between 1953 and 1986, the government pumped an annual average of 360 million gallons of contaminated waste – including plutonium – directly into the groundwater.

Though its first use was in explosives, scientists and engineers have always recognized that plutonium has vast potential as a fuel source. Like U-235, the only naturally fissile isotope, Pu-239 ...

Highly toxic plutonium has seeped into the soil outside the troubled Fukushima Dai-ichi nuclear power complex in northeastern Japan, officials say. The amounts detected in two different soil ...

The separation of plutonium by civilian reprocessing has far exceeded plutonium use in breeder and light-water reactor fuel with the result being a global stockpile of over 300 tons of civilian but ...